The invention relates to an indicator for indicating safety conditions to a pilot during take-off of an aircraft.
During a take-off run, an aircraft accelerates until a critical air-speed is reached at which time the aircraft can become airborne. Clearly, the acceleration must be such that the critical speed is attained before the end of the runway. Acceleration depends upon a number of factors including loading of the aircraft, slope of the runway, and air pressure and temperature. Above all, however, the acceleration depends upon the engine power applied. It is customary for a pilot to apply maximum engine power during take-off although, except in the most critical conditions, maximum power is not necessary. It has been found that running aircraft engines at maximum power considerably shortens their useful life and it is desirable to be able to judge a take-off so that the aircraft becomes airborne before the end of the runway with adequate, but not excessive, power being applied. This demands considerable pilot skill 18 and an object of the invention is to provide an instrument which will assist the pilot in these judgements.